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