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)(11,13,15,16)(17,18)(19,21)(20,22)(23,24)(25,26,31,37,30,28,29,33)(27,32,38,40,34,36,35,39)(2,5)(6,8)(9,11,12,15)(10,13,14,16)(17,19,20,23)(18,21,22,24)(25,27,30,34)(26,32,28,36)(29,35,31,38)(33,39,37,40)(3,7)(6,8)(11,15)(13,16)(25,28,30,26)(27,32,34,36)(29,33,31,37)(35,40,38,39)(1,3,4,7)(2,6,5,8)(18,22)(21,24)(27,34)(32,36)(35,38)(39,40)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.