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