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