The graph peaks represent the periods of active nutrient absorption, which often happens when you consume fast carbohydrates. However, there is no direct correlation between the consumption of carbs and the shape of the graph. Rather the size and shape of the graph indicate the intensity, or the speed, of the absorption process.
The line above the X-axis colored in pink represents your calorie intake. The lighter, shaded color means the data are not final yet. The purple line below the X-axis represents the burned calories.