I found it helpful to add something like this to alter the prompt with color when in intel mode:
if [ "i386" = $(arch) ]; then
export PS1="%F{red}%m:%1d>"
fi
Above sets the prompt to show the machine name and directory in red as a prompt when in intel model, and normal black from the prior:
export PS1="%m:%1d>"
in my .zshrc file.
The difference is the %F{red} prepended to the normal prompt setting...