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