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