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