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