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