Wa alaykum assalam warahmatullah

 

In the Name of Allah, the All-Merciful, the Mercy-giving

 

All praise is due to Allah. Peace and blessings be upon Prophet Muhammad.

 

As long as the picture is in a place where you do not have to see and there is no other place to pray in, your prayer inside your room is valid. May Allah accept it from you.

 

But you should take this opportunity to invite your roommate to Islam. Gentle admonition and kind treatment may attract her heart to Islam.

 

Your Islamic manners and Islamic code of conduct constitute practical da`wah. Imagine how great will be your reward, if you manage to guide a non-Muslim to Islam.

 

Prophet Muhammad (peace and blessings be upon him) said, “By Allah! If a single person embraces Islam at your hands, that will be much better for you than red camels.” (Al-Bukhari)

 

Almighty Allah knows best.