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