You could go to a book store to find an artist's instruction book on oil painting, which will likely include a colour mixing chart. You can also look on the Internet. The number of websites for artists is growing. The Internet is a great tool for artists to connect and exchange ideas and know-how.
Another way to develop an oil colour mixing chart is to make your own. To start, you could combine two pigments at a time in equal quantities. Dab each colour on to some canvas board. For instance, start with a dab of alizarin crimson. Next to it put a dab of titanium white. Then add the two together in equal quantities to give you your third colour in the row, a pale rose colour. For a quick reference you can mark a plus and equal sign so you know what colours to combine to recreate the shade. This is a great way to learn about colour mixing. Although it won't be as tidy as a store-bought colour mixing chart, it will get you to experiment with colour.
Another way to develop an oil colour mixing chart is to make your own. To start, you could combine two pigments at a time in equal quantities. Dab each colour on to some canvas board. For instance, start with a dab of alizarin crimson. Next to it put a dab of titanium white. Then add the two together in equal quantities to give you your third colour in the row, a pale rose colour. For a quick reference you can mark a plus and equal sign so you know what colours to combine to recreate the shade. This is a great way to learn about colour mixing. Although it won't be as tidy as a store-bought colour mixing chart, it will get you to experiment with colour.