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