One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,8)(4,6)(5,7)(9,10)(11,15)(12,16)(13,17)(14,18)(19,22)(20,23)(21,24)(25,26,32,30)(27,36,31,33)(28,35,29,34)(37,39,38,40)(1,3,6,5)(2,7,4,8)(11,18)(12,20)(14,15)(16,23)(25,27,32,31)(26,33,30,36)(28,37,29,38)(34,39,35,40)(9,11)(10,14)(12,19)(13,18)(15,17)(16,21)(20,24)(22,23)(25,28,32,29)(26,34,30,35)(27,37,31,38)(33,39,36,40)(1,2,6,4)(3,7,5,8)(9,11)(10,15)(12,19)(13,18)(14,17)(16,22)(20,24)(21,23)(25,29,32,28)(26,35,30,34)(27,37,31,38)(33,39,36,40)(1,4,6,2)(3,7,5,8)(9,12,13,20)(10,16,17,23)(11,19,18,24)(14,21,15,22)(25,30,32,26)(27,33,31,36)(28,35,29,34)(37,39,38,40)(1,5,6,3)(2,7,4,8)(9,10)(11,14)(12,16)(13,17)(15,18)(19,21)(20,23)(22,24)(25,31,32,27)(26,33,30,36)(28,38,29,37)(34,39,35,40)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.