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