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