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