Pretty color!
It kind of looks like red ink marks? The bag is mis-shapen and wrinkled so I would probably give it a bath in Dawn dish soap and warm sudsy water. While it is in the bath use your fingers to gently rub the stained areas to see if you can remove and of the marks or at least make them lighter and less noticeable.
Next rinse the bag well, allow it to drain into the sink a bit. Lay it out on a towel to shape it, stuff it with clean towels to shape it correctly and carefully lay the straps so that they will dry nice and even. Turn and re-arrange the shape of the bag periodically while it is drying.
After drying overnight, remove the towels and pull the lining out of the bag as much as possible, again lay the bag in a nice, normal shape and allow it to continue drying, turning occasionally.
When it is still a bit damp, apply a good leather conditioner (like Leather CPR) to the bag, apply sparingly, wipe off excess, and massage it into the leather. Wait a few hours and buff with a soft clean rag or a soft clean horsehair brush. Repeat the conditioning if the leather seems dry.
If it still looks dull in spots, you can apply a higher gloss conditioner, like Lexol or Leather Therapy Restorer and Conditioner. A product called Black Rocks Leather n Rich really does a nice job restoring shine but you have to apply it very lightly and wipe it off quickly then brush.