40 container fields in a grid format on your layout would do it. So would a single row of 4 container fields in a list view where your record set consists of 10 records. This could also be 4 container fields in a 10 row portal.
But that puts either 4 fields for images or 40 fields for images all in one record and this is rarely the best option.
You can also replace those individual fields with one row portals with a container field inside the portal row and then use either a "horizontal portal" format or portal filters to control which image appears inside which portal.
And here's a completely different approach if this is for printing/preview mode/save as PDF use:
Use layout setup to specify columns for your layout and then a set of records with one container field for each record can be arranged into a grid format. But only if you are not in Browse mode when you look at the images on your screen.
Genius (as ever). Its the pdf version that I need. I have set up 4 columns but only 3 columns of images appear on my screen. How can I get the four that I want ?
What we are doing here is essentially creating a "labels" layout, but for your container fields.
While in Layout mode, use print set up to specify the desired page size and orientation. (Make sure that the same settings are in place when you preview your layout.)
You should get vertical dotted lines that represent the 4 columns that you have specified for your layout.
Then, make the width your layout narrow enough to fit inside just 1 column.