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