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