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)(11,19)(12,21)(13,17)(14,16)(15,18)(20,23)(22,24)(25,26,30,32)(27,33,35,34)(28,29,37,38)(31,39,40,36)(2,5)(6,8)(9,11,15,14)(10,16,18,19)(12,22,13,20)(17,24,21,23)(25,27,29,36,30,35,38,39)(26,31,28,33,32,40,37,34)(1,3,4,7)(2,6,5,8)(9,12,15,13)(10,17,18,21)(11,20,14,22)(16,23,19,24)(25,28,29,32,30,37,38,26)(27,34,36,31,35,33,39,40)(9,13,15,12)(10,17,18,21)(11,20,14,22)(16,24,19,23)(27,35)(31,40)(33,34)(36,39)(9,14,15,11)(10,16,18,19)(12,22,13,20)(17,23,21,24)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.