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