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