Ingres did a lot of harem scenes that contained lesbian interaction, but these were emphatically not for any lesbian audience but for the titillation of rich men.
Off the top of my head I can think of Gustave Courbet who did quite a sensitive portrayal of lesbian lovers in 'The Sleepers.'
Toulouse-Lautrec is another who who had something of a penchant for drawing women living and loving together, some say it had something to do with his mother who may have been a lesbian (but I'm not sure about that.)
With a little more research I'm sure I can find many more. I guess throughout history men have been fascinated with lesbianism as a world closed to them. That's all I can think of at the minute. Can anyone else suggest artists?