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