A medal, designated as the "active service medal", shall be awarded to any person who is serving with or has served with the National Guard of Colorado in any campaign or period of federal active duty under call or order of the president of the United States. This medal shall be awarded pursuant to regulations issued by the adjutant general. A clasp showing the dates only of such active service will be worn on the ribbon of the medal, and there shall be one clasp for each separate period of active service.