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