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