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