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