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)(11,19)(12,16)(13,14)(15,17)(18,24)(20,23)(21,22)(1,2)(3,6)(4,7)(5,8)(9,11,15,12)(10,16,17,19)(13,20,24,22)(14,21,18,23)(25,26)(27,32)(28,33)(29,34)(30,31)(35,39)(36,37)(38,40)(1,3,5,4)(2,6,8,7)(10,17)(11,12)(14,18)(20,22)(26,31)(29,39)(32,37)(33,40)(9,12,15,11)(10,16,17,19)(13,20,24,22)(14,23,18,21)(25,27)(26,32)(28,34)(29,33)(30,36)(31,37)(35,38)(39,40)(1,4,5,3)(2,7,8,6)(9,13)(10,18)(11,20)(12,22)(14,17)(15,24)(16,23)(19,21)(25,28)(26,33)(27,35)(29,37)(30,38)(31,40)(32,39)(34,36)(9,14,15,18)(10,13,17,24)(11,21,12,23)(16,20,19,22)(25,29,30,39)(26,34,31,35)(27,33,36,40)(28,37,38,32)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.