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