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