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