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