Since I don't know perl at all, i've managed to convert the section that generates the graph into a bash script. The RRD package that the perl script uses has a command line tool called rrdtool and it can be used to generate the same PNG file.
Here is an example which will grab the data from last month:
rrdtool graph\
/home/httpd/html/graphs/green-mtd.png\
--start 20100401 --end 20100501 -aPNG -i -z\
--alt-y-grid -w 600 -h 100\
--color SHADEA#EAE9EE\
--color SHADEB#EAE9EE\
--color BACK#EAE9EE\
-t "$titletraffic"\
-v "$legend"\
DEF:incoming=/var/log/rrd/GREEN.rrd:incoming:AVERAGE\
DEF:outgoing=/var/log/rrd/GREEN.rrd:outgoing:AVERAGE\
VDEF:inctotal=incoming,TOTAL\
VDEF:outtotal=outgoing,TOTAL\
\
"COMMENT:\\s"\
"COMMENT: "\
"COMMENT: Maximum"\
"COMMENT: Average"\
"COMMENT: Current"\
"COMMENT:\\n"\
\
"AREA:incoming#00FF00:Incoming traffic"\
"GPRINT:incoming:MAX:%12.3lf %sBps"\
"GPRINT:incoming:AVERAGE:%12.3lf %sBps"\
"GPRINT:incoming:LAST:%12.3lf %sBps\\n"\
\
"LINE1:outgoing#0000FF:Outgoing traffic"\
"GPRINT:outgoing:MAX:%12.3lf %sBps"\
"GPRINT:outgoing:AVERAGE:%12.3lf %sBps"\
"GPRINT:outgoing:LAST:%12.3lf %sBps\\n"\
"GPRINT:inctotal:Total Incoming\\:%12.3lf %sB\\n"\
"GPRINT:outtotal:Total Outgoing\\:%12.3lf %sB\\n"
It doesn't look exactly the same due to spacing, the title, and the legend, but for the most part it's there. This type of graph could be incorporate into the WebUI if a user was so inclined to write the code to accomplish it. I'm not that person though, perl is not my forte.
Even so, if this was incorporated into the UI it doesn't include the address of who was using the bandwidth, it doesn't include the IP address of individual work stations.