Across the map, there are a number of Spider-Bots, all of them with distinct themes and colour schemes. (There is even a little J. Jonah Jameson Spider-Bot!) They don't show up on the map, so you have to find them while you're out exploring. You will see, however, that they do appear on your mini-map, in the bottom-right corner of the screen.

Here is the icon for the Spider-Bots on your mini-map:

Once you have picked up one of these icons, all you need to do is follow it until you see the telltale shimmer effect. These purply shimmers give away the location of each Spider-Bot as you get in their vicinity.

The shimmer looks like this:

You can also press the  and, on the map screen, hover over each borough to see how many Spider-Bots remain in that area. There are 42 in total, and you will need to get them all to unlock this trophy.