http://www.math.lsa.umich.edu/%7Eikriz/colored.jpg
Please forgive me for tooting my own horn, but you might be interested in this link and this link (scroll down to the section "sporadic simple puzzles"). I worked on these puzzles around the same time that I learned about basic group theory, and thinking about them really helped clarify certain ideas (such as group actions, conjugation, and the utility of studying the orders of groups and their elements). I think they could be quite valuable as teaching aids.