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