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