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