Nope, you cant change the animation of any power.
The only way i've noticed is the other powers have 'flat' animations that are horizontal with the floor. Darkest night has a 'cloudy dome' effect around their feet that stands proud of the ground.
However I agree, it's slightly harder to notice in a big fight than a particular piece of hay in a haystack. (Yes even a needle is too easy to spot, compared to darkest night)
.. 
I'm going to sound like I'm trying to shoot this topic down: when in actual fact, I agree completely!
Anchor it on a boss, and bind a warning to others not to attack the boss, it's easier that way too. It's tactical, you weaken the boss, then wickle down the minions, then you can tackle the boss without fear of the minions overpowering you. I always found it much easier to fight one boss, then 10, 20 etc. minions.
/bind z "say Don't attack $target! He's my anchor for Darkest Night"
I might be wrong on the exact bind, but I use something similar. To make it easier. make a file called anchor.txt, put:
z "say Don't attack $target! He's my anchor for Darkest Night"
And then load the bind file, I don't know the exact code again, maybe someone else can help... but yeah, you get the idea...
P.S. I'm NOT trying to patronize either. If you already know this, then someone else reading the thread who doesn't, can find out.
If you really think the Darkest Night Anchor is kinda hard to see you should just try a Storm Defender in City of Heroes. The Snow Storm Anchor is just impossible to detect, even if the mobs are standing still...
I have experience of using both Darkest Night (I struggle to spot the anchor myself) and Rad Infection (anchor is easy to distinguish) at mid levels and teaming with users of both at higher levels.
When teaming with friends and solo I'd like DN's anchor to be a bit more visible, sure. But in pick-up teams I see no difference with either power - the anchor always dies early, even if I choose an Lt/minion at the back of a spawn and notify my team. So in teams now I tend to just use DN/RI as a boss debuff that I stick on the most dangerous enemy (preferably not one a stalker is getting ready to assassinate). Anchor debuffs really shine in AV/Hero/EB fights, of course.
Notifying the team which enemy will be anchor doesn't help much - there are usually multiple enemies in the same spawn with the same name - and it becomes meaningless in the chaos when everything is moving around and lots of particle effects are going off. Also if you can find a uniquely-named enemy in the spawn to be anchor then it tends to be a mob that needs to die fast because it's especially dangerous.
Perhaps debuff anchors should have a symbol of an actual ship anchor above their heads to mark them out as such. It might be immersion-breaking for some, but surely no more than having the UI onscreen in the first place.
I Agree here Miss_Gunst I had an Ice/Ice corruptor with snow storm, and to be honest i'm struggling to find a harder analogy than a piece of hay in a haystack...but you are right, Snowstorm is the worst by far! 
Can the darkest night animation be changed? Its an anchor power but it is kind a hard to see whose the anchorespecialy if there are other dark powers flying everywhere like tar patch and gloom.