Your Fuju Sagres probably came with a fairly flat, narrow saddle with a narrow cutout (at least that's what's on the 2004's).
To me, that saddle looks like it's skimpy in the rear for supporting MOST womens' sit bones. You may be well served by replacing the saddle.
Most shops will let you try out a new saddle - i.e. they'll help diagnose the problem, suggest something, and allow you to return it for another try if it doesn't make a difference after one or two rides. Just make sure to keep all of the packaging, and don't ride it in really bad weather - ie. make sure you can return it to them in salable condition. (I work for a bike shop that would allow you to do that, no problem...)
As other posters have noted, the Terry Butterfly (emphasis on BUTT???) is a great saddle. I've used Terrys for years - but a different model, the Liberator Lite Ti.
The Sagres is an upright flat-bar road bike. That means that you may find that a saddle that's designed for upright or offroad riding is more comfortable. The stock saddle is a road-oriented saddle which is designed for a more forward riding position than you may be using (though obviously I don't know how you're positioning yourself on the bike). Why'd they do that (put a road saddle on a bike that is not going to be ridden that way)? Who knows...
You don't say if the soreness is more of a squish!!! thing or a chafe!!! thing. My guess is that it's more of a squish (by this I mean you feel bruised, not raw, down there). Getting a saddle that's wider at the rear will help with squish-type problems by taking the pressure off of the tissue in the middle in favor of the bony parts at the back. If it's a chafe!! thing, that can be relieved by a wider cutout (sometimes, though that can move the chafing to on the sides of the cutout), and/or by using a lubnricant along with your padded shorts to reduce friction between you and the bike. Along with Vaseline or Bag Balm., try A&D ointment or (my favorite) Freeman Peace of Heaven Ultra Thick and Rich Body Butter (find it in the beauty products sections at some drugstores...recently I've scored at Target for $4.00 for an 8-ounce tub). The latter has a lot of uses around the house