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