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