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