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