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