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