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