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