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