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)(28,36)(29,33)(30,31)(32,35)(37,40)(38,39) 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)(25,27,29,30)(26,31,33,34)(28,35,37,38)(32,36,39,40)(1,3,4,8)(2,5,6,7)(25,28)(26,32)(27,35)(29,37)(30,38)(31,36)(33,39)(34,40)(9,12,14,13)(10,16,17,21)(11,19,20,22)(15,23,18,24)(26,33)(31,34)(32,39)(36,40)(2,6)(5,7)(9,13,14,12)(10,16,17,21)(11,19,20,22)(15,24,18,23)(25,27,29,30)(26,34,33,31)(28,35,37,38)(32,40,39,36)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.