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