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