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)(13,14,16,21,18,22,17,19)(15,23,24,28,26,27,25,20)(2,4)(5,7,9,8)(6,10,11,12)(14,19)(16,17)(20,23)(21,22)(24,25)(27,28)(2,4)(5,8,9,7)(6,10,11,12)(13,14,18,22)(15,20,26,28)(16,19,17,21)(23,24,27,25)(13,15)(14,20)(16,25)(17,24)(18,26)(19,23)(21,27)(22,28) involution — undirectedA 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.