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)(17,21,19,26)(20,27,24,25)(1,2)(3,4)(6,9)(10,12)(14,16)(15,23)(21,26)(25,27) involution — undirected(2,4)(13,15,19,25,18,23,17,27)(14,20,21,22,16,24,26,28)(2,4)(13,16,18,14)(15,24,23,20)(17,21,19,26)(22,25,28,27)(5,7,8,11)(6,10,9,12)(13,17,18,19)(14,21,16,26)(15,25,23,27)(20,28,24,22)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.