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