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