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