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