Very nice diagram, Jazaaki Allaahu Khayran.
The reason the Shamsiyya (sunny) letters are so called is because the word Shams (sun) starts with the letter sh (sheen) which is one of the letters that diffuse the L in Al. Thus the word Al-Shams (the sun) is pronounced Ash-Shams. The flip side, the Qamariyya (lunar) letters are so called because the word Qamar (moon) starts with the letter Q (Qaaf) which is one of the letters that let the L in Al be pronounced. Thus, the word Al-Qamar (the moon) is pronounced Al-Qamar.