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