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