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