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