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