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