Basically, it is permissible to trade in cosmetics. Some non-practicing women may go outdoors while having them on, but if this happens you are not responsible. In such a case, the sin will be on the users, unless you know that this particular woman is going to use such things in a haram (prohibited) way, in which case you are not permitted to help her in that.
Dr `Ali Muhyy Ad-Din Al-Qurra Dhaghi, professor of the Principles of Islamic Jurisprudence at the Faculty of Shari`ah Qatar, states: “Goods that are used for both lawful and unlawful purposes like cosmetics are, in principal, lawful to sell. The sin will be on the one who uses it in haram (prohibited) ways. However, if the seller is sure that a particular person is going to use these things in a haram (prohibited) way, then he is not allowed to sell it to that person. This is the view of the majority of Muslim jurists. Furthermore, they say that basically it is permissible to sell grapes which may be used in making wine or just eaten as a fruit, yet, if the seller is sure that a certain person is going to use the grapes to make wine, he is not permitted to sell them to the buyer.