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