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