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