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