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