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