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