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