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