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)(25,26,31,39,30,28,29,34)(27,35,40,32,36,33,37,38)(1,3,4,8)(2,5,6,7)(9,10,13,16)(11,17,18,14)(12,21,20,15)(19,22,24,23)(25,27,30,36)(26,32,28,38)(29,40,31,37)(33,39,35,34)(2,6)(5,7)(9,11)(10,14)(12,19)(13,18)(15,22)(16,17)(20,24)(21,23)(25,27)(26,33)(28,35)(29,37)(30,36)(31,40)(32,34)(38,39) involution — undirected(3,8)(5,7)(11,18)(14,17)(19,24)(22,23)(25,28,31,34,30,26,29,39)(27,35,40,32,36,33,37,38)(9,12,13,20)(10,15,16,21)(11,19,18,24)(14,22,17,23)(26,28)(27,36)(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.