You can try draw2d
f(x, a) := sqrt(a) * exp(-(x-a)^2);
fmax(x) := sqrt(x);
flist: makelist(f(x, a), a, [0, 0.5, 1, 2, 5]);
par: map(lambda([f], explicit(f, x, -1, 10)), flist);
par: append([explicit(fmax, x, 0, 5), color=red], par);
load(draw);
apply(draw2d, par);