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)(29,37)(32,36)(34,40)(38,39) involution — undirected(1,2)(3,7)(4,8)(5,6)(9,11,15,12)(10,16,13,18)(14,19,22,20)(17,23,21,24)(25,26)(27,31)(28,30)(29,32)(33,35)(34,38)(36,37)(39,40)(1,3,5,4)(2,7,6,8)(10,13)(11,12)(17,21)(19,20)(26,28)(31,33)(32,36)(38,39)(1,3,5,4)(2,7,6,8)(9,12,15,11)(10,16,13,18)(14,20,22,19)(17,23,21,24)(25,27,30,35)(26,31,28,33)(29,34,37,40)(32,38,36,39)(9,13,15,10)(11,16,12,18)(14,21,22,17)(19,23,20,24)(25,28,30,26)(27,33,35,31)(29,36,37,32)(34,39,40,38)(1,4,5,3)(2,8,6,7)(9,14,15,22)(10,17,13,21)(11,19,12,20)(16,23,18,24)(25,29)(26,32)(27,34)(28,36)(30,37)(31,38)(33,39)(35,40)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.