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