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