Hi @Aaron_Ross welcome to the Percona forums!
In general you’ll find that the MySQL Instances Overview dashboard is going to look in detail at just a subset of your environment, that is, the Top 5 graphs will select only 5 services, and the Top graphs will be the 1 highest instance.
In the case of Top InnoDB I/O Data Reads, this is the formula:
reads / (reads + writes + fsyncs)
It tells us what percentage of InnoDB disk activity is based on reads.
The colour coding is based on green up to 60%, then orange and red above this. Here is the configuration block from the graph definition:
