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