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