One very easy way to do this is via a Definition Query on your layer. Add a new field to your feature class and for the polygons to highlight, calculate the new field to 1 or "Yes" or whatever term you want. Then switch your selection and calculate the other polygons to NOT show on the map as 2 or "No" or whatever term you want.
Then in the Layer Properties->Definition Query, perform a definition query where NewField = "Yes" and click OK. Only those polygons meeting the query show. Add the same layer to the map again below the first layer, perform a query where NewField = "No" and click OK. Only those polygons meeting the query show. Symbolize those layers and a clear outline for example. I'm sure there's other ways of accomplishing the same task but this is the first that popped to my mind.