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