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