Seeing high cache and buffer numbers is usually a good sign, as it means the system is making full use of the memory you have. It’ll automatically deallocate it if something actually needs the memory, but until then it’s using it to store data you might need.
Swap’s a funny one, and whilst you can tune it to an astonishing degree, the decisions the kernel makes aren’t always what you’d want. With this little actual memory usage, compared to the installed RAM, you might be able to run without swap at all, unless you want something like hibernate. If you want to test that, you can run (as root) swapoff -a, which should disable all swap devices, pushing needed pages back in to RAM, but only until you reboot. If it’s stable, you can consider removing the swap partition(s) later.
The cache usage being higher on a server than a laptop seems fairly likely as more disk accesses are occurring. When data is loaded from disk, the linux kernel will keep it in memory even after the original requester is done with it, on the principal that it might need it again. This is the cache you’re seeing. If the kernel detects high memory utilisation it will free cache pages before anything else, so you actually want to see near 100% memory utilisation all the time, as it means fewer accesses to disk.
The swap usage is harder to diagnose without more detailed diagnostic work, but you can see from the graph you posted that, even what swap is being used, you have a little free memory. This may well be the kernel preemptively moving little used memory pages to the swap cache so tgat they can be evicted from memory quickly if needed. You could investigate thus by adjusting the ‘swapiness’ value closer to 0, to see if that delays the swap usage and reduces the peak.