Soaking in water works for me.
Put the colander in the pot, fill it with water - preferably before it dries out in the first place - and then leave it alone until you are ready to do the dishes, whether that's after dinner or (gasp!)
in the morning.
Either way the starch will slip off easily.
cooking.stackexchange.com/users/304/Kate Gregory
In my opinion, the most important part is to rinse immediately after use.
If you use the collander, then let it sit for a few hours (through dinner) or 'til the morning, you're going to have to soak and/or scrub.
A quick spray-down immediately after using will save you a ton of work later: pour pasta into collander.
spray down the pot (I have a pull-out sprayer, and I spray around the edge where the ring formed at the water level; you can give it a quick swipe with a scrub sponge, but you have to be careful about soap near the sink if there's a collander of pasta sitting in there))
dump out the pot (not over the collander)
pour the stuff in the collander back into the pot or whatever serving vessel.
spray down the collander (both sides) & move to the dish drain for full cleaning later
cooking.stackexchange.com/users/67/Joe
If there is some build-up then a soak in mild borax solution will get colander shiny new again.
However, starch will then again want to stick even more easily...
Prevent it with a wee spray of non-stick.
I justify my use in that I spare a good deal of hot water in the clean up.
cooking.stackexchange.com/users/6638/Pat Sommer
I am aware that I address the question indirectly.
What I have observed is that starch is a problem only if the concentration of starch in the water is high.
What I do, is to make sure that I cook the pasta in way more water than most people do.
I try to use at least 1-2 L of water for every 50g of dry pasta.
The main reason why I prefer to use that much water is because the quality of the pasta turn out considerably better that way.
The easier washing is just a side effect :) Yes, bringing all that water to a boil does take a bit more time.
cooking.stackexchange.com/users/2324/Bogdan Belcea
I've only found that hand-scrubbing works.
I use a soap and Bon Ami (no-scratch cleanser), at least for the colander.
Regular soap and a no-scratch scrubbing sponge works on the pot for me, too.
cooking.stackexchange.com/users/1415/franko
Here's a trick I just discovered.
What I used: Non-Stick dishwasher-safe pot
that's starch-encrusted after 2 years of use, a couple times a week every week.
(Shush, I like spaghetti..)
I've put it through the dishwasher before and tried to scrub it off, but never had any success; it's always looked just as bad after drying of as before I started trying to clean it.
Dawn ultra-concentrated dishwashing liquid (The only dishwashing liquid I've used on pots/pans; I use it because my parents did.
Others will probably work as well) Disposable scrubbing sponge (Very cheap; I found them at Walgreens)
Dishwasher Cascade detergent pacs (powered by Dawn) , for the dishwasher Steps I took: Put a few drops of Dawn in the pot, turn on the faucet at high blast so the agitation makes it foam up. Fill it to the brim.
I only let it soak for about 2 hours, more might work better.
Use the scrub-sponge over the whole internal surface to get off the loose starch.
You shouldn't need to actually scrub hard; I lightly brushed it for a short time, like 2 or 3 minutes, and so much residue was coming off
that had I to rinse the sponge often.
Put it in the dishwasher.
Come tonight, about 80% of the inside of the pot was completely clean of residue, no evidence it was ever there in the first place.
The remaining residue has streaks in it as though the scrubber just didn't get all the surface-starch off.
I'm pretty confident that doing this only one or two more times will have it looking as good as new.
cooking.stackexchange.com/users/20447/Izkata
I looked up how to do it and it seems there is no easy answer.
I decided to try baking soda and vinegar.
It worked pretty well!
I put vinegar in a bowl, got the colander wet with the vinegar, poured baking soda into the colander and scrubbed it a bit.
The abrasive soda helps loosen the starch and the vinegar starts to bubble up.
I left the colander in the bowl of vinegar for a while, scrubbed again and rinsed.
It was a lot better, but needed another round.
I poured more baking soda into the colander, scrubbed and left it in the vinegar again.
It looks so much better.
I might try heating the vinegar the next time to see if it speeds up the process!
cooking.stackexchange.com/users/61613/Stacy
I've always used the Lagostina stainless steel pot cleaner to remove starch stains and it works great! :)
cooking.stackexchange.com/users/64975/colleen
I was always told to rinse the colander or pot with cold water as soon as the food is removed to prevent the starch from setting up on the utensil.
cooking.stackexchange.com/users/22964/Bob
Rinse with cold water immediately, then wash in warm.
Hot water makes the starch turn gluier; cold water releases it.
cooking.stackexchange.com/users/64272/Natalie Keller Chaput
After cooking pasta, I typically drain it in a colander.  I have found the starch residue in both the cooking pot and particularly the colander is difficult to clean without hand scrubbing it.  I am curious if anyone knows a solution - either a method or product that makes clean-up quicker and easier.  Thanks for any ideas you may have!
What is the best method/product for cleaning pasta's starch residue from colander and cooking pot?
cooking.stackexchange.com
<pasta><cleaning>
cooking.stackexchange.com/questions/23732
cooking.stackexchange.com/users/10227/Melanie
Rinse immediately with cold water to prevent the starch from adhering, or soak before washing. Hand scrubbing using a soap and Bon Ami (no-scratch cleanser), dishwashing liquid, baking soda and vinegar or Lagostina stainless steel pot cleaner can work well. It also helps to use more water when cooking to reduce the starch content. You should rinse it as soon as possible and then soak in water. You can clean it with dish soap or baking soda and vinegar. 
Soak in water, then scrub with dish soap or baking soda and vinegar. Rinse it as soon as the food it removed. Cook in more water than needed to dilute the starch.