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