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