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