Hey FireDragon, there's some really nice stuff going on in this synastry. He puts a few planets in your 4th house, with Venus on the IC, which creates a really comfortable and familiar feeling -- like you know him instantly; a very fast rapport and intimacy. Assuming his birth time is right, your Venus in his 8th house and sun in his 7th are often indicators of attraction. Also, your moon trine his Mars and his sun opposite your Mars absolutely add physical spice -- if you get the vibe he's attracted to you, you're probably right. Moon trine Mars in particular is sexy as all get out (one of my very favorite aspects); you respond deeply and instinctually to his masculine energy (whether or not he's a stereotypical 'manly man' ), and there's an attraction that reaches to your core. Both of your moons make some nice aspects to the other person's chart -- I really love his moon trine your Venus; a lot of sweetness and sympathy there.Your Venus is in grounded Taurus while his is in the more flighty Gemini, so you might find his signals inconsistent or hard to read, especially if you can't tell whether his behavior towards you is flirtatious or just how he acts with people in general. His Venus opposite your Uranus can also add instability, or at least a sort of on/off dynamic where he seems interested in you one day and not so much the next (incidentally, this might also be how he perceives you!).
His Saturn/Uranus square your Mercury also adds a bit of communication hesitancy -- you might feel a little self-conscious in expressing yourself and worried about his judgment? Hard to say how a Saturn/Mercury square would play out, since you're also colleagues and that aspect can point to different forms of hierarchy or authority that aren't necessarily personal.
Could you post the composite chart as well? It looks like you might have a sun-Venus conjunction there (just from eyeballing midpoints) as well as composite moon in the 4th house (I could be wrong about that -- again, trying to calculate in my head!), all of which are really wonderful to have in a composite.
Are you in a position to get involved with him without it making things weird at work?