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