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