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