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