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