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