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