You should be able to:
editor.execute( 'highlight', { value: 'yellowMarker' } );
editor.execute( 'highlight', { value: 'greenMarker' } );
editor.execute( 'highlight', { value: 'pinkMarker' } );
editor.execute( 'highlight', { value: 'blueMarker' } );
editor.execute( 'highlight', { value: 'redPen' } );
editor.execute( 'highlight', { value: 'greenPen' } );