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)(11,14)(12,19,20,15)(13,16)(17,23,24,21)(18,22)(25,26)(27,30)(28,31)(29,32)(33,36)(34,37)(35,38)(39,40)(2,5)(6,8)(9,11,13,18)(10,14,16,22)(12,17,20,24)(15,21,19,23)(25,27,29,35)(26,30,32,38)(28,34,36,40)(31,37,33,39)(1,3,4,7)(2,6,5,8)(9,12)(10,15)(11,17)(13,20)(14,21)(16,19)(18,24)(22,23)(26,31)(28,36)(30,37)(32,33)(34,40)(38,39)(10,16)(11,18)(15,19)(17,24)(26,32)(30,38)(31,33)(37,39) 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.