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