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