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