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