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