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