All transistors can be used as inverting switches with the base current about 5% of the collector load current from the same R voltage drop about 20x bigger R value is optimal.
High hFE transistors are preferred like the PN2222A and twisted magnet wire may be used or CAT3, 4, 5 cable.
100 Ohms in the collector to 5V will result in different currents for each colour of LED would be the maximum for 20~30mA LEDs. Increase all values to reduce brightness. @ 20 mA, R/Y ~ 2.1V and G ~ 3.3 V +/- 0.x
Thus if the input is high (5V) the base is ~ 0.7V and collector is from 0.1 to 0.7 (avg=0.4), then the currents for R/Y would be (5-2.1-0.4)=2.5V across R =100(=0.1k) is 2.5/0.1k = 25 mA.
For Grn , (5-3.3 -0.4)=1.3 or 13 mA so you would want twice the brightness for the green LED at 525 nm since it only gets half the current.
The choice of LED brightness (=Iv [mcd] can significantly affect the result due to the quality and size of the internal chip as well, a 3mm or 5mm lens will magnify brightness. [degrees]