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