To my knowledge (the book is large - it would help if you gave scriptures), but graceful generally is used with respect to an earthly object.

In the above cases, graceful is referring to the physical attributes of elegence, light-footedness, beauty, comeliness. You wouldn't generally apply these attributes to God, being without physical form.

Gracious, however, would be expected to be associated with God as it refers to his longstanding patience and un merited forgiveness. "God is gracious in that he does not give us the punishment that we deserve."

It is also possible that 'graceful' is being used instead of 'full of grace'. In such case you could, I believe, consider it a synonym of gracious.

Steve