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