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