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