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