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