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