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