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