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