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