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