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