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