Can I control the colour of the map icons?

Suppose I was using 'Minimap Sidebar' to map all of the places where I could find old books. Now these can be found at 'Secondhand book stores', 'Opportunity/Charity Shops', and even our local Libraries sell their old stock. However, I am more likely to find an interesting book at a 'Secondhand book store' than an 'Opportunity/Charity Shop' (because book stores ONLY sell books). What would be really good would be some way in which I could control the colour of the icon on the map. Say, green for 'Secondhand book stores', blue for 'Opportunity/Charity Shops' and yellow for 'Libraries'. This way I could know the types of shops being displayed on the map. Of course, colour would be one way of visually classifying the map. Numbers or letters could also serve this purpose, if colour is difficult or not suitable. What do you think?