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