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