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