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