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)(25,26,30,32,28,33,29,34)(27,35,38,39,36,31,37,40)(2,5)(6,7)(9,11,12,20,14,22,13,21)(10,15,18,24,17,23,19,16)(25,27,30,38,28,36,29,37)(26,31,32,40,33,35,34,39)(9,11,14,22)(10,16,17,24)(12,21,13,20)(15,18,23,19)(26,32)(27,36)(29,30)(31,39)(33,34)(35,40)(1,3,4,8)(2,6,5,7)(10,17)(15,23)(16,24)(18,19)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.