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)(11,17,18,24)(12,20,21,15)(14,22,23,19)(25,26,29,32)(27,30,34,39)(28,36,37,31)(33,40,35,38)(1,3,5,4)(2,6,8,7)(25,27,29,34)(26,30,32,39)(28,33,37,35)(31,38,36,40)(1,3,5,4)(2,7,8,6)(9,11,12,19,13,18,21,22)(10,14,15,17,16,23,20,24)(27,33,34,35)(30,38,39,40)(1,4,5,3)(2,7,8,6)(11,18)(14,23)(17,24)(19,22)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.