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