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