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)(25,26,31,36,30,35,29,34)(27,37,38,33,28,32,39,40)(1,3,4,8)(2,5,6,7)(9,11)(10,16)(12,18)(13,20)(14,19)(15,22)(17,23)(21,24)(25,27,29,39,30,28,31,38)(26,32,34,33,35,37,36,40)(9,12,14,10)(11,18,19,16)(13,17,15,21)(20,23,22,24)(25,28,30,27)(26,33,35,40)(29,39,31,38)(32,36,37,34)(2,6)(5,7)(11,19)(16,18)(20,22)(23,24)(25,29,30,31)(26,34,35,36)(27,38,28,39)(32,40,37,33)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.