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