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