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