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