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