Love the map but why are all the stations under M1? M1 goes from Matinkylä to Vuosaari and M2 from Tapiola to Mellunmäki. And then there's also M2M which goes from Mellunmäki to Matinkylä and is only mentioned in the English version of the Wikipedia article. And when I checked in HSL.fi it seems to only run twice every evening from Monday to Friday and once an evening on Saturdays. And there are also M1B and M2B who run run from Itäkeskus to Vuosaari (M1B) and Mellunmäki (M2B) in the morning before the first trains arive from Tapiola and Matinkylä.
Those aren't really lines but rather different patterns of services the system provides. Thanks for your feedback though. I would see if I can redesign the map by services rather than lines (。•̀ᴗ-)✧
What I would do is make two columns: M1 and M2 and make stations from Vuosaari to Tapiola appear on the M1 column and stations from Mellunmäki to Matinkylä on the M2 column.