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