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