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