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