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