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