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