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