It's very unlikely that there will be a portrait of him. He appears from his will to have been a moderately well off country 'gentleman'. From this period it's mostly the portraits from the very wealthy which survive.
The so called portrait of his son, Humphrey doesn't seem to be right either. It appears as an illustration by a 19th Century artist, Frederick Barnard. It represents Mr Valiant for Truth in an edition of the Pilgrim's Progress (p259)