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)(11,20)(12,23)(13,26)(14,18)(15,32)(16,22)(17,30)(19,31)(21,37)(24,34)(25,36)(27,38)(28,33)(29,40)(35,39) involution — undirected(2,5)(6,8)(9,11,14,22)(10,16,18,20)(12,15,25,31)(13,27,29,21)(17,33,35,34)(19,36,32,23)(24,39,28,30)(26,37,40,38)(1,3,4,7)(2,6,5,8)(9,12,15,22,14,25,31,11)(10,16,19,23,18,20,32,36)(13,28,30,21,29,24,39,27)(17,34,26,37,35,33,40,38)(9,13,15,30,14,29,31,39)(10,17,19,26,18,35,32,40)(11,21,12,24,22,27,25,28)(16,33,23,38,20,34,36,37)(2,5)(6,8)(10,18)(16,20)(17,35)(19,32)(23,36)(26,40)(33,34)(37,38) 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.