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