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