I want to use Markdown to store textual information. But quick googling says Markdown does not support color. Also StackOverflow does not support color. Same as in case of G
While Markdown doesn't support color, if you don't need too many, you could always sacrifice some of the supported styles and redefine the related tag using CSS to make it color, and also remove the formatting, or not.
Example:
// resets
s { text-decoration:none; } //strike-through
em { font-style: normal; font-weight: bold; } //italic emphasis
// colors
s { color: green }
em { color: blue }
See also: How to restyle em tag to be bold instead of italic
Then in your markdown text
~~This is green~~
_this is blue_