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