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