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