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