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