Color chat in single player is very possible, using /tellraw and command blocks.
Command:
/tellraw @a {"text":"Hi.","color":"red"}
This will produce "Hi." in the traditional "&c" color. However, it broadcasts to everyone.
To send a message to one person, just replace the "@a" with a player's name. You can type this command into the regular chat.
/tellraw SilverShadow97 {"text":"Hi.","color":"red"}
Hope this helps!