It seems that Grace was somewhat the opposite of Calvin, in that she had a sparkling personality. So it stands to reason that given her status and attributes, there ought to have been a number of portraits painted of her.
And there were. Except that there are few decent images of them to be found on the Internet, and some original works might have gone missing. Below is what I've been able to locate here and there on the Web thus far.
this source. I like this one better than the official portrait. Too bad I can't locate a decent image of it on the Internet.
Frank O. Salisbury and his portrait of her. Again, I couldn't find an image of the portrait.