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)(25,26)(27,33)(28,35)(29,32)(30,31)(34,38)(36,37)(39,40) involution — undirected(1,2,5,8)(3,4,7,6)(9,11,15,12)(10,16,17,13)(14,19,24,20)(18,23,22,21)(25,27)(26,28)(29,37)(30,35)(31,33)(32,38)(34,39)(36,40)(1,3)(2,6)(4,8)(5,7)(10,17)(11,12)(18,22)(19,20)(26,31)(28,33)(32,40)(36,38) involution — undirected(1,4)(2,7)(3,8)(5,6)(9,12,15,11)(10,13,17,16)(14,20,24,19)(18,21,22,23)(25,28)(26,27)(29,38)(30,33)(31,35)(32,37)(34,40)(36,39)(1,3)(2,4)(5,7)(6,8)(9,13)(10,12)(11,17)(14,23)(15,16)(18,19)(20,22)(21,24)(25,29,30,39)(26,32,31,40)(27,34,35,37)(28,36,33,38)(1,4)(2,7)(3,8)(5,6)(9,14,15,24)(10,18,17,22)(11,19,12,20)(13,21,16,23)(25,27)(26,28)(29,37)(30,35)(31,33)(32,38)(34,39)(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.