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