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