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