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)(11,15)(12,16)(13,14)(19,23)(22,24)(26,30)(27,33)(28,36)(38,40)(2,4)(3,8)(9,11,14,16)(10,12,13,15)(18,21)(22,24)(26,30)(28,36)(31,34)(35,39)(2,4)(6,7)(10,13)(11,16)(17,18)(19,22)(20,21)(23,24)(25,26,29,30)(27,34,33,31)(28,32,36,37)(35,40,39,38)(1,3)(2,6)(4,7)(5,8)(9,12)(10,11)(13,16)(14,15)(17,19)(18,22)(20,23)(21,24)(25,27,29,33)(26,31,30,34)(28,35,36,39)(32,38,37,40)(1,4,5,2)(3,7,8,6)(9,13,14,10)(11,12,16,15)(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.