Network patch panels with nicely bundled wires might work; switches often have numerous blinky lights.

You could dig up some antique gear and make it run: tape loader robots or even 9 track tapes with reels. It's been a long time since they did flashy innards on display stuff like that so its in the uncomfortable range between "scrap" and "industrial antiques" now.

Or just admit it's all for show and commission an artist to make something cool. We have better blinky lights technology than ever before with addressable RGB LED strips and panels and many examples of their use.

You can tell the bosses that putting real production servers on display would be a security issue. say "Tempest" and nod knowingly. As long as you dont smirk they'll usually go along.