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