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