Here's an intermediate version of Barton's recommendation.
Have maxima produce TeX; save that in a file and edit the TeX.
Sometimes people want a very particular form. x-y, -y+x, -1*y^1+1*x^1, ...
e^(-x), exp(-x), 1/exp(x), 1/e^x ....
I would generally discourage people from trying to get Maxima's simplifier
to produce
the more unusual variations.