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