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)(17,18,21,20)(19,22,24,23)(25,26,30,31)(27,28,35,32)(29,37,38,33)(34,39,40,36)(3,7)(5,8)(11,15)(13,16)(17,18,21,20)(19,23,24,22)(26,31)(28,32)(29,38)(34,40)(1,2)(3,5)(4,6)(7,8)(9,11,12,15)(10,13,14,16)(17,19,21,24)(18,22,20,23)(25,27,30,35)(26,32,31,28)(29,34,38,40)(33,39,37,36)(1,3)(2,5)(4,7)(6,8)(9,10)(11,13)(12,14)(15,16)(17,20,21,18)(19,23,24,22)(25,28,30,32)(26,27,31,35)(29,36,38,39)(33,34,37,40)(1,2)(3,5)(4,6)(7,8)(25,29,30,38)(26,33,31,37)(27,34,35,40)(28,36,32,39)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.