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