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