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