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