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