Colors

The E38 was available with 38 different colors as standard option, plus a variety of colors from the BMW catalog under "Sonderlackierung", which translates to "Special Color".
These were usually any color regularly available in the BMW Catalog, such as Estoril Blue. However, almost *any* color was available, even from other manufacturers. For example, Geneva Green Pearl (Honda), Smaragdschwarz Metallic (Mercedes-Benz) or even Ferrarirot (Ferrari)!
Standard Colors:
Sonderlackierung (490) – 5689 E38s produced with this color code.
Here are a few examples:
Standard colors:

ALPINWEISS 3 (300) 
ANTHRAZIT METALLIC (397)
ARKTISGRAU METALLIC (269)
ARKTISSILBER METALLIC (309)
ASCOTGRUEN METALLIC (353)
ASPENSILBER METALLIC (339)
BIARRITZBLAU METALLIC (363)
BROKATROT METALLIC (259)
CALYPSOROT METALLIC (252)
CANYONROT METALLIC (343)
COSMOSSCHWARZ METALLIC (303) 
CRIOLLO METALLIC (446)
FJORDGRAU METALLIC (310) 
GLACIERGRUEN METALLIC (334)
GRANITSILBER METALLIC (237) - Available but 0 E38s were produced with it.
IMOLAROT 2 (405)
IMPALABRAUN METALLIC (418)
KASCHMIRBEIGE METALLIC (301)
MOJAVEBRAUN METALLIC (331)
NACHTBLAU METALLIC (453)
NAVARRAVIOLETT METALLIC (346) 
ORIENTBLAU METALLIC (317)
ORINOCO METALLIC (406)
OXFORDGRUEN METALLIC (324)
OXFORDGRUEN 2 METALLIC (430)
PEARLBEIGE METALLIC (411)
ROYALROT METALLIC (390) 
SAHARABEIGE METALLIC (443)
SCHIEFERGRUEN METALLIC (449)
SCHWARZ 2 (668)
SIENAROT II (362) - Available but 0 E38s were produced with it.
SORRENTBLAU METALLIC (360)
STAHLBLAU METALLIC (372)
STERLINGGRAU METALLIC (472) - Available but 0 E38s were produced with it.
STRATUS METALLIC (440)
TITANSILBER METALLIC (354)
VERMONTGRUEN METALLIC (356)
VIOLETTSCHWARZ 2 (304) - Available but 0 E38s were produced with it.
Sonderlackierung (490) - 5689 E38s produced with this color code.

Here are a few examples:

ATLANTIS METALLIC (399)
BARBADOSGRUEN METALLIC (247/6)
CARBONSCHWARZ METALLIC (416)
ESTORILBLAU METALLIC (335) 
FASHIONROT II (R 65728.0 Herberts) or (402/3)
HELLROT (314)
JADEGRÜN (078)
LIGHTBEIGE RR 9520123 (CPU 8"14"36.00)
LIMONIT METALLIC (352)
MORAROT METALLIC (359)
PETROL-MICA METALLIC (305/5)
ROMANTICROT METALLIC (369)
SKARABAESGRUEN METALLIC (444)
SEPIA VIOLET METALLIC (474)
VEILCHENBLAU METALLIC (FE 86-50GU BASF)
VELVETBLAU METALLIC (379)