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