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