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