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