Really there is only one major symbol to focus on in this poem, and that is the woman that acts as the muse to the painter. It is obvious that this woman acts as a symbol as she stands for herself, but also, in the imagination of the painter, she stands for so much more, as "she fills his dream." In a sense, she is a blank canvas onto which he can impose his own male fantasies and desires, creating endless duplications of her face, but in different guises. Note how the poem tells us that:
Every canvass means
The same one meaning, neither more nor less.
Although the paintings of the woman cast her in a number of different roles, making her into a saint or an angel, what is similar is the way that the artist completely ignores the real woman in front of him and merely "feeds on her face" to produce his male representations of her. Thus the woman is a symbol of the way Victorian society and art treated women and in particular did not allow them to have their own identity.