To the end of documenting colors, connectors, and connections for the MPCNC stepper motors …
At the stepper motors:

The plug for the stepper at the end of the harness:

I opted to match the “pin 1” marks on the connectors, because that’s easy to remember, although it puts the pin latches on opposite sides:

Some obligatory Kapton tape holds the two connectors together.
The joint at the middle of the harness, with the near-end stepper cable on the upper left:

At the RAMPS driver end of the cable:

The Z-axis extension cable, with the stepper cable on the right:

I plugged the cables into the RAMPS board with the “pin 1” mark at the A1A2 end of the connectors.
With all the wires in place (and the GT2 drive belt still in its bag), I stuck masking tape tabs on the motor shafts, connected the RAMPS board, and verified the directions:

Although the Y axis needed reversing, both pairs of motors turned in the same direction!
Being that type of guy, I reversed the Y axis direction in the firmware configuration, because it’s easier for me to make all the physical connections look the same than (try to) remember to flip the Y axis connector whenever I must reconnect the cable to the driver.