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