Hi Max,
The LED current is regulated at about 20mA each, and is determined by R1. That reminds me, you can get rid of R2 and ground pin 8.
You can use any kind of LEDs: red, blue, white , UV or even a mixture of colours.
The scan rate is determined by the 470K resistor and is about 1/2 second.
You can use a 1M linear pot in series with a 180K resistor instead of the 470K resistor if you want to adjust it from 380ms to 1.25 seconds.
This circuit will make all the LEDs off during the other half of the flasher's time.