While there isn't a direct way to use conditional formatting with SUM to add numbers based on cell color in Excel, there are a couple of workarounds you can use:

Method 1: Using SUMIFS with Conditional Formatting Criteria

1. Apply Conditional Formatting: Apply the conditional formatting that defines the cell color for your desired categories.
2. Identify Criteria: Take note of the specific formatting criteria used for each color category (e.g., font color, background color, cell value range).
3. SUMIFS Formula: In a separate cell, enter the SUMIFS formula. This formula allows you to sum based on multiple criteria.

Here's the general structure:

```excel
=SUMIFS(range, criteria_range1, criteria1, criteria_range2, criteria2, ...)
```

- range: This is the range of cells containing the numeric values you want to sum.
- criteria_rangeN: This specifies the cell range(s) containing the conditional formatting criteria for each category (e.g., the cell used to define the background color rule).
- criteriaN: This defines the specific criteria to match for each category. Here, you'll enter the formatting rule used (e.g., the exact background color reference or a comparison based on the value that triggers the formatting).

Example:

Let's say you have cells A1:A10 with values and conditional formatting applied to highlight cells with values greater than 50 in green and less than or equal to 50 in yellow. You want to sum the green and yellow values separately.

In cell B1 (for green values):

```excel
=SUMIFS(A1:A10, A1:A10, ">50")
```

In cell B2 (for yellow values):

```excel
=SUMIFS(A1:A10, A1:A10, "<=" & 50)
```

Method 2: Using FILTER with SUM

1. Filter Data: Use the filter functionality to isolate the data based on the desired cell color (green or yellow in this example).
2. SUM Formula: In a separate cell, use the SUM function to add the filtered values.

Example:

Assuming the same scenario as above, you can filter column A to show only green cells (values > 50). Then, in another cell, use the SUM function to add the visible green values. Repeat the filtering process to show yellow cells and use SUM again.

These methods allow you to achieve the desired results of summing values based on the colors assigned through conditional formatting.

Additional Notes:

* For complex conditional formatting rules, Method 1 with SUMIFS might require more adjustments to the criteria definition.
* Method 2 with filtering is generally simpler but requires manual filtering for each category.
* Consider using helper columns to store the color information extracted from conditional formatting for easier use in formulas (advanced technique).