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