[webnrrd2k]

If you liked that, then you'll love Visual Group Theory[1]. The first two chapters are online, and I believe free and legal to download [2].

[1] From the publisher's site: https://www.maa.org/press/books/visual-group-theory

[2] http://www.mathcs.emory.edu/~dzb/teaching/421Fall2014/VGT-Ch...

Previously on HN: https://news.ycombinator.com/item?id=11745486