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