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