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