E185: Cannot find color scheme*

For those using Plug as plugin manager, the problem may be solved by setting the color scheme after declaring the plugin that provides the theme:

call plug#begin()
Plug 'rakr/vim-one'   " tell Vim to load the theme/plugin
call plug#end()

colorscheme one       " set the color scheme after the theme provider has been loaded

This sounds like a problem with your 'runtimepath' option. If you use a plugin manager, these usually extend that. The default location should be ~/.vim/colors. Please check with

:set runtimepath?

There should be a ~/.vim in there (or equivalent).

If all else fails, you could also just :source /full/path/to/your/color.vim