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