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