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