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