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