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