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