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)(11,19)(12,15)(13,22)(14,18)(16,20)(17,23)(21,24)(25,26,28,30)(27,31,34,37)(29,32,35,38)(33,40,36,39)(1,3,4,8)(2,5,6,7)(9,11,13,12,14,20,23,21)(10,15,17,19,18,24,22,16)(26,30)(27,33)(29,35)(31,39)(34,36)(37,40)(2,6)(5,7)(25,27,28,34)(26,31,30,37)(29,36,35,33)(32,39,38,40)(2,6)(5,7)(9,12,13,20,14,21,23,11)(10,16,17,15,18,19,22,24)(26,30)(31,37)(32,38)(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.