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