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