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