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