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