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