Most popular Test Station cabinets are 19inches wide to accept 19 standard equipment.
The high depends on the number of equipment to be included.
When the high is limited one can setup a two bay station.
Many manufacture provide different depth to accept long equipment or wiring service loop(space for wiring).
Companies my have a standard color to be used on all their equipment(check).
Below are some sample layout of Single and Two bay Test stations.