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