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