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