The schema is available from the StyleManager.GetSchema method. So you can call this method in your code to return the schema. If you want to save it to a file so you can look at it, you could do something like this:

            string fileName = Path.Combine(Path.GetDirectoryName(Application.ExecutablePath), "appStylistSchema.xml");
            System.Xml.Schema.XmlSchema schema  = StyleManager.GetSchema(true);           
            FileStream fs = new FileStream(fileName, FileMode.CreateNew);
            StreamWriter sr = new StreamWriter(fs);
            schema.Write(sr);
            Process.Start(fileName);