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