One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,7,5,3,6,8)(9,10,14,19,15,21,31,20)(11,22,24,37,26,39,25,33)(12,18,27,36,28,17,13,29)(16,32,34,40,35,30,38,23)(9,11)(10,16)(12,23)(13,30)(14,24)(15,26)(17,33)(18,37)(19,34)(20,38)(21,35)(22,29)(25,31)(27,32)(28,40)(36,39) involution — undirected(1,3,4,8,5,2,6,7)(9,12,14,27,15,28,31,13)(10,17,19,29,21,18,20,36)(11,23,24,32,26,40,25,30)(16,33,34,22,35,37,38,39)(2,3)(7,8) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.