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