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