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