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