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