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