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