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