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