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