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