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