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