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