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