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