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