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