Text coloring in zsh
You can color your text in zsh by using the %F{...} syntax. To view all available colors use:
for i in {1..256}; do print -P "%F{$i}Color : $i"; done;

To reset the colors use the special value %F{reset}.
Usage example
I am displaying the current time in on the right hand side of my terminal, in dark gray. The clock will conveniently stop for executed tasks, so that I automatically can see when I started that particular task.

You can do that by using the following config in your .zshrc:
# Show timestamp whan a command
# was issued in the right prompt
RPROMPT='%F{240}%D{%H:%M:%S}%F{reset}'
TMOUT=1
TRAPALRM() {
zle reset-prompt
}
Other Shells
Users of bash can use this guide: When did I run that command?