time domain plot from built in 'fskmod' function

hi.....

 am trying for obtaining time domain plot of the results from the built in 'fskmod'function.....

M = 4; freqsep = 8; nsamp = 8; Fs = 32;
x = randint(1000,1,M); % Random signal
y = fskmod(x,M,freqsep,nsamp,Fs); % Modulate.
ly = length(y);
% Create an FFT plot.
freq = [-Fs/2 : Fs/ly : Fs/2 - Fs/ly];
Syy = 10*log10(fftshift(abs(fft(y))));
plot(freq,Syy)

i want the plot of modulated signal.....i.e. QFSK with 4 distinct carriers.