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