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