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