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