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