Assuming I could do anything but sit absolutely still, staring, weeping silently? Run, through objects, people, borders. Put as much distance between myself and the spider as possible before my muscles burn out or my lactic acid build up causes enzyme malfunction on a fatal scale.
I think spiders are incredible, and I try at all opportunities to save them. They're among my favourite animals for so many reasons, but I am terrified of them. Tiny spiders aren't a problem, large house spiders terrify me, however tarantulas I'm okay with. The fur, girth, and, in the species I've encountered (by design =P), docile nature, makes them appear less as spiders to the irrational bit of me that sets off every warning system in my body at the thought of certain species being anywhere near me.
The one you describe though, I imagined having no fur just a prominent exo-skeleton, huge legs (long), and a comparatively small body. Combined with the vivid colours, and it's proximity to me, I would likely be paralysed with fear. I could see a picture of it with relative impunity though, which wasn't always the case. I'll itch a little :/