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