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