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