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