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