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)(11,20)(12,21)(13,19)(14,18)(15,17)(16,22)(23,24)(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)(10,16)(12,17)(13,21)(14,22)(15,24)(18,20)(19,23)(26,31)(27,36)(29,30)(32,35)(37,38)(39,40)(9,12,15,20,14,23,13,16)(10,11,19,21,18,22,17,24)(25,27,29,38,28,37,30,36)(26,32,33,35,31,39,34,40)(2,6)(5,7)(9,13,14,15)(10,17,18,19)(11,21,22,24)(12,20,23,16)(26,31)(27,37)(33,34)(36,38)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.