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