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