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