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