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