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