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