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