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