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)(15,21)(16,19)(17,26)(18,24)(20,25)(22,27)(23,28)(5,7)(6,9)(8,12)(10,11)(13,14,16,19)(15,22,23,18)(17,20,25,26)(21,24,28,27)(6,10)(9,11)(13,15,17,24,16,23,25,27)(14,18,20,21,19,22,26,28)(7,12)(9,11)(13,14)(15,22)(16,19)(17,20)(18,23)(21,27)(24,28)(25,26) involution — undirected(1,3,4,2)(6,10)(9,11)(14,19)(15,23)(20,26)(24,27)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.