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