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