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