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