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