You don't need a SCART cable at all, they're just plentiful and relatively cheap so you'd be guaranteed to get a cable & plug with all the pins connected to wires (rather than trying to buy the correct plug, 10 wires and a long shrink-wrap for them all). You need a proper plug for the back of the Saturn to get all your wires connected and a scart cable will have that. You could make up a female SCART-to-d-sub cable and use it to connect the Saturn as well as many other consoles into your monitor (Genesis, SNES, PS1, PS2, Dreamcast, XBOX, etc.), but if Saturn's all you're interested in, you can get a Saturn SCART cable, cut the SCART plug off, and connect the wires to the correct pins of a d-sub (VGA) plug.
AppleQueso mentioned a sync splitter and looking at the manual, it appears you will need that wired into the cable (Saturn has composite sync - horizontal and vertical combined, and your monitor seems to need the sync on 2 separate pins). I know there's one wire on most all video connectors that has some voltage in it - for the saturn it's pin 4 on that diagram, so it should be possible to make that circuit work without providing external power. Aside from that you should be able to just wire the rest of the pins straight across to the correct pins on the d-sub plug.
I've always received high quality cables from
retro_console_accessories -
http://www.retro-access.com/ and
Rob Webb @ ConsoleGoods. I hear
Playasia is reliable as well.
over half of the SCART cables I bought from other places were duds. Incorrectly wired, missing the capacitors and/or missing the necessary sync wiring.
Reguarding Retro_console_accessories - considdering the professional job they do of making up all their cables and the fact that they do modding services, they might be willing to custom-make the cable you're looking for.
I had to spend an hour or so on Google to find the right wiring diagrams for the cable I made up for my 1084 monitor. I expect there's several people that have done exactly what you're planning to do. Most of the useful, correct information I found was on the
Arcadecontrols forum. Those guys are very well versed in connecting arcade monitors to all kinds of hardware.
Reguarding the sync splitter, I think this is one:
http://www.nexusuk.org/projects/vga2scart/circuitbecause to make a useable composite sync, I just soldered the horizontal and vertical sync wires together...
If you're not thoroughly confused yet, one last note - Japan and Europe have different wiring for their SCART plugs - Only use European SCART.