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