The Shulchan Aruch writes (134:2; listen to audio for precise citation) that the person who removes the Torah scroll from the Heichal for the reading must show the writing of the Torah to everybody in the synagogue, including the women. Upon seeing the writing of the Torah, the congregation must slightly bow and recite the verse, "Ve'zot Ha'Torah Asher Sam Moshe Lifnei Benei Yisrael." The Arizal (famed Kabbalist, Israel, 1534-1572) held, based on Kabbalah, that one should come close enough to the Torah to be able to read the actual letters, for then the spiritual light of the letters will surround and influence a person. Therefore, the person removing the Torah from the Heichal must ensure to bring the Torah near the ladies' section in the synagogue so that they, too, can see the writing of the Torah scroll.
Sephardic custom allows women to attend the synagogue services and look upon the Torah scroll even during their state of Tum'a (ritual impurity, such as during the period of Nida). Although many Ashkenazim are stringent in this regard, according to Sephardic custom women may attend services and look at the Torah regardless of their current status with regard to Tum'a.
Women do not, however, bear an obligation to hear the Torah reading. Therefore, if a woman arrives in the synagogue as the Torah is taken from the Heichal, after she looks at the Torah she may recite Shacharit, even as the Torah is read. (This would be forbidden for a man.) In fact, if she wishes she may leave the synagogue during the reading in order to pray Shacharit in the hallway. It is forbidden for both men and women to speak during the Torah reading in the synagogue. Therefore, the Be'er Moshe (work of responsa by Rabbi Moshe Stern of Debereczyn) ruled that if a woman finds it difficult to refrain from talking during Torah reading, it is preferable that she leave and not hear the reading at all, since, as mentioned, women are not required to hear the reading.
Summary: It is a Mitzva for both men and women to look at the Torah scroll when it is taken from the Heichal for the reading. Women are exempt, however, from listening to the reading. Therefore, a woman may leave during the reading to pray Shacharit, and if she finds it difficult to remain silent during the reading, it is preferable that she leave the sanctuary.