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