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