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