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