I'm going to separate my answer into several parts.
I. Type of reader
There are 3 types of people that uses graphs:
a) The people that can read any graph.
b) The ones that hardly can read a graph.
c) Those who are looking for a very specific info.
I won't care about the 1st kind. Any ugly graph will do.
For the type b you need a lot of effort, interactive graphs, several graphs showing different approaches (by day, by week, over all time, by day, by week) moving graphs, cartoons...
But the approach in most cases should be thinking that the user needs to see a very specific data.
I am assuming that you know what kind of data your reader is looking for.
In your graph, the most important thing is the overall hours of study in one week, and how you performed in the different weeks. If that is what you need, this type of graph is okay.
The rest of the data is not important in your graph.
II. The visual info
Okay, so as I'm assuming that you chose the right type of graph and approach, and because this is the graphic design site, I will analyze your graph.
1) Nobody on the planet reads the hours in terms of that many decimal points.
"I studied 4.1582 hours... !!" Reduce the decimals to just 1.
Eliminate all the 0 that have no sense, by deleting them in your excell table.
2) If in the bars the days goes up (Monday on the bottom and Sunday on the top) the brain of the reader must jump between contradictory dimensions when reading at the color-day table: left to right are in the reality bottom to up. Put your color-day table in the same vertical dimension as the bars.
3) Don't repeat the same info. This title is the same as the chart title.
4) Don't repeat week, week, week, week, week...
3-4) Make this titles easier to read, use a better font size. The objective of a graph is to see all the info at a glance.
5) The overall proportion and spacing of the chart (between columns) gives the sensation of being too much data. Make it more pleasant.
6) You can give some visual aids like this tiny lines, that connect Monday with Monday, etc.
7) Make the overall visual style more pleasant. The info can be the same, but if it is presented in a more interesting way, the observer will try to look in depth the info.
I could not find a way to put the total hours data on the top of the column. Probably it is usefull.
I didn't find the way to increase the size of the color squares next to the days. That would be easier to read.