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