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