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