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