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