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