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