Combinatorica

The following function in the Mathematica Combinatorica package ShowGraphArray[Partition[FiniteGraphs, 4]] produces the following graphic.

I found it in the book 'Computational Discrete Mathematics, Combinatorics and Graph Theory with Mathematica, by Sriram Pemmaraju and Steven Skiena, Cambridge 2003.' It's not the typical Proposition / Proof mathematics book but it does give you access to about 450 -practical- freely available ( if you have Mathematica ) tools to extend your problem solving toolkit.