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