To access the malware log, click the Logs... button in the Scan Overview window.
You can also access the logs by choosing Window > Logs from the top menu bar, or press Command-Option-L.
The log looks as follows, although of course your log will show different entries from this one.
You can click the small disclosure triangle for any completed scan log entry. This will provide additional information such as the location of any infected or corrupted file found during the scan: