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