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