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