Common-cathode LEDs suck

Or sink. Whatever. No matter which word you use, there's a need for the logic to source a current of 25mA (or reasonably close).

I definitely prefer LED banks with anodes tied to the positive power rail. NPN and NFET transistors are more efficient per unit area than their PNP or PFET counterparts, so interfacing LEDs usually can be done using microcontroller GPIO pins to sink the current (but be sure to check the rated sink current, the ADuC7025 makes no promises of more than 1.6mA), and a series resistor to make up the voltage difference. Open-drain logic outputs preferred but not necessary, the LED becomes high impedance as the cathode voltage goes high. Even when the microcontroller can't sink enough current, NFET or NPN transistors are available in quad-packs (or more) with high current gain.

With common cathode, this is not so easy. Furthermore, the common cathode is already hard-wired to ground, but that's the most reasonable thing to do with common cathode anyway. Since we need external components, my preference would be to go for a current-controlling LED driver. If we were using LEDs with the usual common anode/switched cathode arrangement, there'd be lots of options including programmable dimmers and so forth. But all hope is not lost, Exar makes "high-side" LED drivers with a controlled output current (PWM for dimming) with either two or three channels on a single chip. Problem: one shared enable for all channels. Huh, how's that multi-channel then? Well, these chips are designed to match current (and hence intensity) between multiple LEDs. There's no options for separate control or even single-channels, and if you only connect one LED the logic promises to be so kind as to detect a fault and turn off your good channel. There used to be a quad driver chip made by TI and National Semiconductor designed as the high side of a matrix scan system, the SN75491, that would have been perfect for this, but it is no longer sold. Abandon hope all ye who enter here.

So we're left with using transistors for voltage control, combined with series resistors to intersect the 3V @ 25mA spec of the LEDs. Since there don't seem to be any triple- or quad-pack PNP (or PFET) transistors, one option would be discrete transistors like the 2SB1694 or FDN338P. PFET is better, because the low current gain of PNP causes a respectable load remaining on the microcontroller. But I'm a proponent of low part count anyway, so a multi-channel inverter will be an even better option as long as it has appropriate supply voltage and current source capability. Several alternatives are TI's SN74LVC3G04 and ON Semi's MC74AC04. Neither option recognizes 3.3V as logic high, and the hex inverter has lower input and supply current requirements, so I'll use it. The restrictive lower limit on logic high won't be a problem, since the ADuC7025 is 5V-tolerant and bidirectional GPIOs can always simulate open-drain outputs by setting the data directionality bits while keeping the logic level low. A pull-up resistor to 5V completes the circuit.