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