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