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