Easy.
So God's like a balloon, and we're all inside the balloon. God sticks his fingers into the balloon from the outside, so the balloon fingers are inside the balloon. Those fingers are the Son. Then the fingers move around and do stuff. The movement of those fingers is the Holy Spirit. And what those fingers accomplish while moving around, is Grace.
So how can God be both the balloon and the hand poking into the balloon?
Well, God is like a tree. The trunk of a tree is solid like the balloon, but the branches can bend all the way around and poke into the trunk.
And that's it. God is like a tree acting like a balloon, and thereby manifesting the Father, Son and Holy Spirit.
All these things spoke Jesus unto the multitude in parables; and without a parable spoke He not unto them. Matt 13:34
:o)