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