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