The SELinux coloring book [pdf]
This trend of using illustration to explain complex topics is really wonderful. I know that people may criticize it as childish, but I find it helpful and enlightening.The illustrations that I've found most amazing and well done are created by people like:Lin Clark (https://code-cartoons.com/)Julia Evans (http://jvns.ca/zines/)Linda Liukas (http://www.helloruby.com/)Amy Wibowo (https://shop.bubblesort.io/)You may notice a trend with the gender of the authors above. I personally believe that women have a better sense for simplifying complex ideas, and greater empathy and patience for teaching those ideas once they've been made simple.