How are Macbeth and Lady Macbeth's states of mind after the murder expressed through their speeches and actions?
Well, as you'd expect, the two of them are very jumpy! Have a look at this extract, and the sharp, quick lines that they speak, thinking that someone has discovered them:
MACBETH: I have done the deed. Didst thou not hear a noise?
LADY MACBETH: I heard the owl scream and the crickets cry.
LADY MACBETH: Now.
MACBETH: As I descended?
LADY MACBETH: Ay.
Shakespeare creates real tension - particularly as "Hark!" ("listen!") implies a pause, as the couple anxiously listen for a response.
As for their states of mind, Macbeth's language becomes more and more heightened (and almost mad!) as he considers the murder he has just committed:
Me thought I heard a voice cry “Sleep no more!
Macbeth doth Murder sleep”—the innocent sleep,
Sleep that knits up the ravell'd sleeve of care,
The death of each day's life, sore labor's bath,
Balm of hurt minds, great nature's second course,
Chief nourisher in life's feast—
Lady M is baffled by these speeches, and remains hurriedly practical, asking him "what do you mean", taking the daggers back to the crime-scene herself, and - eventually - making the ominous encouragement that "a little water clears us of this deed".
Macbeth is thoughtful, maddened, poetic; Lady Macbeth is practical, very aware of her situation, prosaic. Macbeth even repents his deed in the scene's final lines: "Wake Duncan with thy knocking: I would thou couldst".
The irony of this, of course, is that by the end of the play these roles are reversed: Macbeth reflects painfully coldly on his future, and Lady Macbeth goes mad.