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