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