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