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