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