Do you mean this effect?

It should be enabled by default.
To change the color syntax, go to Window --> Preferences and type color in the upper left search box. Then all color settings will be filtered.
You can change the color of matching tags in General ---> Editor ---> Text Editors ----> Annotation .

You can also try this Eclipse Color Theme plugin , which already includes many popular color themes.
PS All settings are based on version 1.7 Indigo eclipse version.
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