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