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