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