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