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