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