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