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