Answer
ArcGIS shows CAD data in two different ways: as CAD drawings and as CAD feature datasets. CAD drawings are rendered using the colors specified in the CAD drawing file. You can turn the individual layers on or off, but you cannot change their symbology. CAD datasets contain point, line, polygon, and annotation feature classes. You can change the symbology of CAD feature classes in ArcMap from the Symbology tab of the Layer Properties dialog box.