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