Monokai is a colorscheme for 24bit truecolor terminal, originally ported to vim by Damien Gombault (first seen here).
The original repos still live, although it hasn't been updated since 2009. This repos serves only to allow monokai.vim to be installed using modern plugin managers for vim/neovim.
There's also a vim.org Script page for this colorscheme.
Add to your .vimrc:
" Recommended for neovim users.
Plug 'nvim-treesitter/nvim-treesitter', {'do': ':TSUpdate'}
Plug 'uchenily/monokai'
Don't forget to :PlugInstall
after editing your config files.
Fetch it over the net and store it locally in your .vim/colors
folder:
cd ~/.vim/colors
curl -G https://raw.githubusercontent.com/uchenily/monokai/master/colors/monokai.vim -o monokai.vim
You can use nvim-treesitter/playground :TSHighlightCapturesUnderCursor
to find highlight matches under the cursor, it is useful when you want to customize color theme.