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