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