Looking at pictures of shirtless male tau page 5 of the new dex, page 61 and page 53 of the old Dex, shows that they have different muscles on their chests and tend to have a long lean body, suited to the grace they are supposed to have. Also, I do not see any nipples on the males, leading me to thing that females do not have mammary (heck they might not even be mammals) glands.
After all, why should Tau have the same birth cycle/raising system as humans do? In fact I would say because they live a different amount of years, I would be it is almost a given with quicker maturity rates. In so many words, I think I agree with the statment that Tau females look like Tau males.
Xenology as horrible as it is, does provide a look at Tau musculature, and IIRC that is a dead female Tau. Of course, it also has toes and orks have beer bellies.