How come Muslims don't have images of GOD as Christians do with Mary and Jesus?

Because there is nothing like GOD Almighty. Let us look at Noble Verse 42:11 "(He is) the Creator of the heavens and the earth: He has made for you pairs from among yourselves, and pairs among cattle: by this means does He multiply you: there is nothing whatever like unto Him, and He is the One that hears and sees (all things)."
Creating images (idol gods) of GOD Almighty is forbidden in Islam. Many Verses in the Noble Quran prohibt them. Let us look at few of them:
"Verily ye, (unbelievers), and the (false) gods that ye worship besides Allah, are (but) fuel for Hell ! To it will ye (surely) come ! (The Noble Quran, 21:98)". And "Lo! Abraham said to his father Azar: "Takest thou idols for gods? For I see thee and thy people in manifest error. (The Noble Quran, 6:74)"
"We took the Children of Israel (with safety) across the sea. They came upon a people devoted entirely to some idols they had. They said: 'O Moses! fashion for us a god like unto the gods they have.' He said: 'Surely ye are a people without knowledge.' As to these folk,- the cult they are in is (but) a fragment of a ruin, and vain is the (worship) which they practise. (The Noble Quran, 7:138-139)"
"Remember Abraham said: 'O my Lord! make this city one of peace and security: and preserve me and my sons from worshipping idols.' (The Noble Quran, 14:35)"
"Such (is the Pilgrimage): whoever honours the sacred rites of God, for him it is good in the Sight of his Lord. Lawful to you (for food in Pilgrimage) are cattle, except those mentioned to you (as exception): but shun the abomination of idols, and shun the word that is false. (The Noble Quran, 22:30)"