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