Sending 5 Led pixel values to arduino , is this a good way?
I would recommend a similar solution as DaveX with a small modofication.

If you bitmask your LEDS, and leave room for a possible additional 3, you can mask any combination of them in the space of 00-FF. then you could send to the arduino a single string of 0xFFFFFFFF  FF(LED bitmask),FF(Red value), FF(Green Value), FF(Blue Value).

so 
LED 1 {00000001 =01} all red {FF0000} would be 0x01FF0000

LED 2 and  4 {00001010 =0A} all green {00FF00} would be 0x0A00FF00

LED 5 and 1 {00010001 =11} all blue {0000FF} would be 0x110000FF

ALL LEDS off would be 0xFF000000

All LEDS onn full white would be 0xFFFFFFFF