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