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