Well, we are not sure of what you are trying to do with the switches on the left hand side, and because you run the signal from the first strip to the second, the ground must also connect directly from the first to the second. If there is any distance between, then you should add a second resistor in series with the data at the start of the second strip just as there is a resistor which should be at the start of the first strip.
The data must always run along with the ground, so showing it separate from the power wires is a mistake. If anything, you run the power from the 5 V supply directly to the strip, and then run the power - 5 V and ground - together with the data wire, back from the start of the strip to the Arduino so that all are together.
Of course, the rule applies also to the power wiring, you do not separate the 5 V and ground wires at any point in the run. And a 470 µF capacitor should be across 5 V and ground at the start of each strip.