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