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