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