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