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