Spectral analysis graph plot

How do I plot the spectral analysis graph for the signal below? The below code is in the callback of a pushbutton.

Fs=8000;
          Ts=1/Fs;
          t=[0:Ts:1];
          F_A=440; %Frequency of note A is 440 Hz
          A=2*sin(2*pi*F_A*t);
          sound(A,Fs);