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