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