It doesn't appear to plot because e is a scalar. e is a scalar because it's overwritten each time through the loop.
Instead, make e a vector, one element of which is calculated each time through the loop. Then the plot will show up:
clear
for n = 1:10
% e = 1/factorial(n);
e(n) = 1/factorial(n);
end
disp('calculated value for e = ')
disp(e)
percent_error = e/exp(1)*100
plot(1:10,e)
