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