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