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)(11,16)(12,17)(13,18)(14,19)(15,20)(21,22)(23,24)(27,28)(31,32)(35,36)(38,39) involution — undirected(2,5)(6,7)(11,20)(15,16)(21,24)(22,23)(25,26,30,34)(27,31,28,32)(29,33,37,40)(35,38,36,39)(1,2)(3,6)(4,5)(7,8)(9,11)(10,15)(12,21)(13,22)(14,20)(16,19)(17,23)(18,24)(25,27,30,28)(26,31,34,32)(29,35,37,36)(33,38,40,39)(1,3)(2,6)(4,8)(5,7)(9,11)(10,16)(12,21)(13,23)(14,20)(15,19)(17,22)(18,24)(25,26)(27,31)(28,32)(29,33)(30,34)(35,38)(36,39)(37,40) involution — undirected(9,12,14,18)(10,17,19,13)(11,21,20,24)(15,23,16,22)(25,28,30,27)(26,32,34,31)(29,36,37,35)(33,39,40,38)(9,13,14,17)(10,18,19,12)(11,22,20,23)(15,24,16,21)(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.