You can use KSar tool in combination with sar command to generate and analyze server load and other parameters.
1. Install Sysstat rpm in your server.
2. It will provide the sar package.
3. Let sar record data for a day.
4. Run the following command:
# LC_ALL=C sar -A > /tmp/log.txt
5. Install K-Sar in a windows or Linux Box. (The package is available in sourceforge)
6. Import the log file generated in step 4 above.
7. Generate the graph.
Please note that since Ksar is a java based tool, so it can run in both Linux and Windows machines having JRE installed. Just the sar log has to be fed into it to generate the graph as described above.