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