Eclipse color setting for whitespace characters

Basically, it is Foreground color + Transparency, there are no specific settings for whitespace characters.

• Transparency is configurable in

  Preferences > General > Editors > Text Editors: click 'configure visibility' link > Transparency level

• Foreground color is configurable in

  • For Text Editor:

    Preferences > General > Editors > Text Editors: Appearance color options

  • For Java Editor:

    Preferences > Java > Editor > Syntax Coloring: Element > Java > Others

Other editors may have their own settings.

@atlanto's answer is outdated now it seems. From Preferences it is still General -> Editors -> Text Editors but now there is a "configure visibility" option beside the "Show whitespace characters" checkbox label. There you can configure the transparency (default is 80 out of 255) and which characters appear.