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