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