As you can see, we have a squad leader with a couple of very chunky swords. They have small cables running into them so presumably they are power swords/vibroswords or something similar. He also has 2 banner-styles fins containing sensors and communications gear. Next in line are a pair of identical troopers armed with tribarrel support weapons, making good use of the power armour's extra load-carrying capacity.
The bottom row comprises a trooper with some sort of square-barrelled heavy weapon. Maybe it's some sort of heavy flechette gun or launcher. Finally there are a couple of troopers armed with paired shoulder-mounted missile pods which are obviously the same as the single hexagonal-fronted one carried by the heavy weapon trooper in the normal infantry set.
I've followed a pretty similar colour scheme to the regular troopers, using Vallejo beastly brown and charred brown with GW red gore on the shoulder pads, backpack grilles and lower leg details.
The commander has the little sensor windows on his back fins detailed in green for a bit of contrast.
Finally a comparison photo so that you can see how a normal trooper measures up against one in power armour.
I've seen several other reviews where people have commented on the "teddy-bear" shape of the helmet! They are quite cute.