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)(25,26,30,31,29,34,28,33)(27,32,37,38,35,39,36,40)(2,5)(6,7)(9,11)(10,14)(12,19)(13,18)(15,17)(16,22)(20,23)(21,24)(26,31)(28,30)(32,38)(33,34)(36,37)(39,40) involution — undirected(1,3,4,8)(2,6,5,7)(10,15)(11,18)(16,20)(19,24)(11,18)(14,17)(19,24)(22,23)(25,27,29,35)(26,32,34,39)(28,36,30,37)(31,38,33,40)(9,12,13,21)(10,16,15,20)(11,19,18,24)(14,22,17,23)(27,35)(32,39)(36,37)(38,40)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.