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)(11,14,18,22)(12,15,20,24)(17,21,19,23)(25,26,30,32)(27,36,28,34)(29,35,31,39)(33,38,40,37)(1,3)(2,5)(4,8)(6,7)(9,11)(10,14)(12,19)(13,18)(15,23)(16,22)(17,20)(21,24)(26,32)(33,40)(34,36)(35,39) involution — undirected(9,12)(10,15)(11,17)(13,20)(14,21)(16,24)(18,19)(22,23)(25,27,30,28)(26,33,32,40)(29,37,31,38)(34,39,36,35)(3,8)(5,7)(11,18)(12,20)(14,22)(15,24)(25,28,30,27)(26,34,32,36)(29,37,31,38)(33,39,40,35)(2,6)(5,7)(11,18)(14,22)(17,19)(21,23)(25,29,30,31)(26,35,32,39)(27,37,28,38)(33,34,40,36)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.