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