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