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