One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,3,6,4,5,7,8)(9,10)(11,19,22,34)(12,23,25,40)(13,27,28,17)(14,18)(15,21,30,38)(16,26)(20,32,36,35)(24,31,39,29)(33,37)(9,11,13,22,14,20,28,36)(10,15,27,30,18,29,17,31)(12,24,26,38,25,21,37,39)(16,32,40,35,33,19,23,34)(2,5)(6,8)(11,20)(15,29)(19,32)(21,24)(22,36)(30,31)(34,35)(38,39) 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.