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