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