First, make sure that you've read in the time field correctly:
Then, you can create a straight table chart with field 'name' as dimension and
as expression, assuming one arrival time per name value.
Then you've got two options for colour the expression:
Either use the old-style visual cues tab in chart properties, and enter an expression like
in the entry field for upper and lower limit (chosing an appropriate colour also).
Or, second option, use a Text Color attribute expression in expression tab:
Expression could look like
=if( [arrival time] >= maketime(7,45), lightred(), lightgreen() )