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