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