One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,7,8,5)(9,10)(11,18)(12,16)(13,22)(14,17)(15,20)(19,23)(21,24)(25,26)(27,31)(28,32)(29,37)(30,33)(34,39)(35,40)(36,38)(1,3,4,8)(2,5,6,7)(25,27)(26,31)(28,36)(29,34)(30,35)(32,38)(33,40)(37,39)(9,11,14,21)(10,15,17,23)(12,20,13,19)(16,24,22,18)(27,34)(28,29)(31,38)(32,37)(35,36)(39,40)(9,12,14,13)(10,16,17,22)(11,19,21,20)(15,18,23,24)(25,28,30,29)(26,32,33,37)(27,34,35,36)(31,39,40,38)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.