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