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