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