I've only seen that color in canned cream of chicken soup
and I'm dubious of its source.
I personally don't feel like it has to be yellow.
If your goal is just color I would use turmeric-
it is my yellow-stain of choice.
cooking.stackexchange.com/users/2001/Sobachatina
Usually that bright yellow gravy colour is from using bouillon cubes or powder to make the broth, rather than making it yourself.
The OXO cubes are quite heavily colored (not naturally), and will make your gravy yellow.
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Chicken fat is what you want, and--this is important--no cream or milk.
Use chicken fat to make a roux, and then chicken stock.
This will get you a yellowish colour.
For extra bonus points, make your pastry with schmaltz as well.
They do this at the gourmet supermarket down the road, and their chicken pot pies fly off the shelves.
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Turmeric can be used without effecting the taste too much, all though I agree with previous posters with the analysis on why the color is yellow.
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Yellow?
Hm...
the gravy on my homemade pot pie is a pretty off-white, creamy color.
It's colored by the half&half and chicken broth that it starts with.
Perhaps if your chicken broth is yellow-y to begin with and you use more of that?
cooking.stackexchange.com/users/1816/justkt
Turmeric does work to give chicken soup or pot pie
it's yellow color, but the best thing to use is saffron threads.
Just a few threads will turn a whole soup a nice yellow, without altering the flavor.
Saffron is also what is used to make Spanish Paella (rice with chicken, sausage and shrimp).
It can be purchased at specialty grocery stores, like Whole Foods, or sometimes health food stores or online.
It is very costly compared to other seasonings.
(a small vile which might have 10 threads in it for $10.)
Hope this helps you.
PS.
Do not overuse the saffron as a little goes a long way in coloring broths.
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Yellow colored chicken soup can be achieved using chicken feet.
Old Jewish secret
cooking.stackexchange.com/users/10839/jjknowles
Using a brown chicken stock would help the color and provide some extra flavor.
When making your stock, roast the bones before adding them.
Brown the veggies before adding them.
(Some people add a little tomato paste, too.)
cooking.stackexchange.com/users/5263/Steve
I'm making a chicken pot pie. Taste is decent, texture is good, however the appearance of the 'chicken gravy' inside is more....dull gray like than a more vibrant yellow. I don't mind it, but most people eat with their eyes first so....  Is the yellow color artificial or natural, and what can be added/removed to create this?
How do you get a nice yellow gravy color when making a chicken pot pie?
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<chicken><pie>
cooking.stackexchange.com/questions/7079
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The colour of homemade pot pie is usually not yellowish, and this colour is more often seen in canned chicken soup or bouillon cubes or powder. You can achieve a more yellow colour by adding boullion, chicken feet, chicken fat, saffron or turmeric, roasting the bones before adding them and not using cream or milk. You can get that that yellow colour from using a chicken soup or powdered chicken broth or from using the chicken fat or feet in the broth. You can also use saffron or turmeric for the yellow colour.
You only get that colour from canned soup or powdered broth. Chicken fat and chicken feet can give that yellow colour. Try using saffron thread or turmeric. Roast the bones before making your stock.