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