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