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