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