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