How does Lady Macbeth show qualities of her character besides those that are cold hearted and ruthless?
Yes, although she is mostly cold-hearted and ruthless, Lady Macbeth has other traits that can be seen on occasion.
Here, in Act 2, scene 2, Lady Macbeth is bold, scared, and surprisingly sentimental:
That which hath made them drunk hath
made me bold;
What hath quench'd them hath given me fire. Hark! Peace!
It was the owl that shriek'd, the fatal bellman,
Which gives the stern'st good-night. He is about it:
The doors are open, and the surfeited grooms
Do mock their charge with snores: I have drugg'd their possets,
That death and nature do contend about them,
Whether they live or die.
Who's there? what, ho!
Alack, I am afraid they have awaked
And ’tis not done. The attempt and not the deed
Confounds us. Hark! I laid their daggers ready;
He could not miss ‘em. Had he not resembled
My father as he slept, I had done't.
So, just after she says how bold she is, she is frightened by noises. Then she says that line about her father. What a tender accomplice she is.
And after she goes back into the murder room to return the daggers and smear blood on the guards, she even seems so admit a bit of shame and guilt for what she and Macbeth have just done:
My hands are of your color, but I shame
To wear a heart so white.
After this, and through most of the play, Lady Macbeth holds it together pretty well, even while her husband occasionally loses it. Again and again she chastises him for his fear and sense of guilt. But, we know that, eventually, she can't handle her own guilt and finally cracks. She sleep walks and, while doing so, spills the beans about all the murders her husband has committed. Horrified by all that has happened, she says:
Out, damned spot! Out, I say! One–two—
why then ’tis time to do't. Hell is murky. Fie, my lord, fie!
A soldier, and afeard? What need we fear who knows it,
when none can call our power to account? Yet who would have thought the old man to have had so much blood in him?
Do you mark that?
The Thane of Fife had a wife; where is she
now? What, will these hands ne'er be clean? No more o’
that, my lord, no more o’ that. You mar all with this starting.
And then this last admission of a guilt from which she can never rid herself:
Here's the smell of the blood still. All the perfumes of Arabia will not sweeten this little hand. Oh, oh, oh!
Yes, she's been cold hearted and ruthless, a "fiend-like queen," but she has finally succumbed to her own evil.