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