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