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