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