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