the whole face; all of one's face
Literal noun for the entire face. It is more written or descriptive than everyday 顔中, and often appears with に to say that sweat, color, etc. covers the face.
He came back with sweat all over his face.
adverb, noun which may take the genitive case particle 'no'
all over one's face; with one's whole face
Used adjectivally with の or adverbially with に, most famously in 満面の笑み, meaning that an expression is spread across the whole face.
She greeted me with a broad smile.
When their victory was decided, the players smiled all over their faces.
He was running with sweat covering his entire face.
A smile spread across her entire face.
Her whole face turned bright red with embarrassment.